moving any advice?

I wrapped all my scales in white plastic grocery bags (I'd accumulated a lot over time) and put them in the same plastic tote bin. All of the scales being wrapped in plastic bags gave them all padding sorts and for my really precious figures, I double bagged them. I used white bags over other colors because I didn't want to risk discoloring my scales from the bags.

I know it sounds kind of flimsy, just using plastic grocery bags to pack scales - but they were fine and moved with no issues! I would do it again over repacking them in their original boxes because of the amount of time I saved doing so ^^;

I moved with a similar sized collection earlier this year. Luckily, I didn't move very far so I just packed all the figures in their boxes and placed the boxes in moving boxes. I used my own clothes as padding and drove a few rounds. It took a whole day but it was worth it.

I think if I were to move far, I'd rent a large vehicle and ask a friend I trust to drive it or pay extra to a trustworthy moving company to take just the figures one round and the rest of the stuff another time.

Is there any van to rent in your area? If there is, consider renting it. Based on what i've done when i'm moving out, i suggest putting the collections back in their original box and moving them (either partially or all of them if it fits in the van) by yourself just to make sure they're safe. For me, if it should be moved partially, i don't mind doing it back-and-forth until it's done. Although i'm not moving that far, hope this helps even a bit.

how far are you moving? i've moved twice now with my collection, but only within 100 miles of each other. if you are moving close you could bring figures each trip you take, but if you're moving far i would recommend getting a uhaul. i used movers when i went just because of distance. i packed everything back in original boxes, with the blister. then i wrapped each box with moving paper. i made sure to pack the bottoms and sides of the boxes with moving paper. i used the large boxes and made sure that i filled any little hole with cushioning.

I'd also vote for renting a van and I'd put the figures back in the original box and then put those in a moving box via tetris-ing. If there's any gap, fill them up with balled up newspaper (newspaper is much cheaper than bubble wrap) and of course, don't overstuff the moving box like its bulging out.

It'll make life so much easier if you can hand carry multiple figures in a large moving box rather than each individual box at a time that might slip out of your hand while doing multiple trips between car and your new place.

Work Smart not Hard.

I'm actually moving too with a similarly sized collection.XD What I'm doing is packing the figures in their boxes in moving boxes. I pack them so that they don't move around at all and use packing material to fill the odd gaps since most boxes don't perfectly fit together. Since you'll be handling them carefully, you don't need to stuff the boxes with packing material like you would when mailing them. You can if you want, but you'll need way more boxes. Also, it's surprisingly disappointing how few figures will fit in a moving box compared to what you expected (unless you mostly have nendos). Then you can carefully pack these moving boxes in a uhaul van or trailer and be on your way. My figures have been safe so far.

Don't know how far you're moving but if it's more than a few trips your little car can handle. I personally would rent a U-haul van/truck, pack the figures in their boxes if possible, if not bubble wrap or some of that polyester fiber fluff you can find at any craft store and transport them with anything else soft that I own. Such as blankets, pillows, even clothing, basically anything that'll keep them from moving around as I'm driving and won't damage them.

I'm quite curious about this too as I'm in a similar situation.

When I move, I wont be moving far, so I plan to just find a few large boxes that could fit in my trunk and back seat, bubble wrap them the best I can, and just take them in batches over.
Have a room be specifically no entry for moving crew or anyone else, and just set them all on the floor as I move them over.
Then just make trips, lots of trips.

Rent a van/truck/trailer or find a furniture or general moving company nearby tbh. You can just put them in moving boxes, tight, they should survive in their original packaging and maybe a bit of bubble wrap.

I think a van might be ideal for your situation.

You're going to have rent out some kind of trailer or something, if you're going to drive to your new house. And a more powerful car, if your current one doesn't have enough horsepower to tug it. If you're going to rely solely on your car you can skip out on the protective material for the figures since you'll be driving carefully and on well maintained roads. However I feel that 300 figures are going to take more than one trip and if you're going cross country you might get a few weird look from border guards. And if they decide to frisk your car if they suspect you're carrying something illegal that would be a huge pain.
Otherwise, it would be best to wrap your figures in bubble wrap individually or in combinations and then put them in huge boxes and have them shipped. Unfortunately, moving them all is going to cost a lot and you're going to have to find a good moving company since I've heard some don't really understand what "Fragile, handle with care" means.